At this point it starts restore and begins. Unfortunately it returned an error again with only 36% remaining:
Restore: Input/output error restoring MFS data.
Restore: /dev/sdc113: No such file or directory.

As for WinMFS, I left the computer on all night and all day while I was at work and it still said "processing", so I cancelled it last night and tried again - same thing. Should I be waiting more than 24 hours?

No, 24 hours is way more than enough time.

You need to run the drive maker's own diagnostic software long test on your target drive(s).

Even if it's brand new.

Always do that before putting a drive into service--"stuff" can happen during shipping.

Also, has this drive ever been attached to a GigaByte brand motherboard, or used in something other than a TiVo?

Amazon currently has the 2TB WD20EURS for $95, and any of the 3 Series 3 models can use it if they've already been updated to version 11.0k of the TiVo OS.

However, /dev/sd"x"1 is a partition on /dev/sd"x", which is proper form when mounting it to access a file on that partition, but when restoring to a drive, you don't restore to a partition on the drive, you restore to the drive itself and the restoration process creates the needed partitions, so it would be more like

You need to run the drive maker's own diagnostic software long test on your target drive(s).

Even if it's brand new.

Always do that before putting a drive into service--"stuff" can happen during shipping.

Also, has this drive ever been attached to a GigaByte brand motherboard, or used in something other than a TiVo?

Amazon currently has the 2TB WD20EURS for $95, and any of the 3 Series 3 models can use it if they've already been updated to version 11.0k of the TiVo OS.

However, /dev/sd"x"1 is a partition on /dev/sd"x", which is proper form when mounting it to access a file on that partition, but when restoring to a drive, you don't restore to a partition on the drive, you restore to the drive itself and the restoration process creates the needed partitions, so it would be more like